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Study of the Safety Factor for Tunnel Stability Considering the Stress Release Effect
(1 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071;2 Department of Architectural Engineering, Logistical Engineering University of PLA, Chongqing 400041)
Abstract The actual deformation of a primary lining is far greater than the elastic deformation of a tunnel, and the plastic deformation occurs later. In this paper, surrounding rock is quantified by taking the primary lining as an elastic-plastic material and adopting the FEM numerical limit analysis method, and the interaction between the rock and lining is studied with a characteristic line method. The results show that the safety factor of the surrounding rock remains unchanged under a small stress release rate, while support efficiency decreases under a stress release rate exceeding a certain value and therefore the safety factor of the surrounding rock is reduced. A method for calculating the safety factor of surrounding rock after a stress release is proposed based on the FEM strength reduction and characteristic line methods, providing a theoretical basis for tunnel design.
Abstract：
The actual deformation of a primary lining is far greater than the elastic deformation of a tunnel, and the plastic deformation occurs later. In this paper, surrounding rock is quantified by taking the primary lining as an elastic-plastic material and adopting the FEM numerical limit analysis method, and the interaction between the rock and lining is studied with a characteristic line method. The results show that the safety factor of the surrounding rock remains unchanged under a small stress release rate, while support efficiency decreases under a stress release rate exceeding a certain value and therefore the safety factor of the surrounding rock is reduced. A method for calculating the safety factor of surrounding rock after a stress release is proposed based on the FEM strength reduction and characteristic line methods, providing a theoretical basis for tunnel design.
2016, Vol. 53 